Woody Biomass Woody Biomass OverviewOverview

Energy Demand

• Worldwide demand for fossil fuels projected to increase dramatically over the next 20 years

• Fossil fuel will come from politically unstable countries or undesirable locations

• The US uses more fossil fuels than the next 5 highest consuming countries

• Fossil fuel-related energy costs continue to rise

Climate Change

• Climate change is occurring• CO2 is one of several major

greenhouse gases• Climate change will impact

the planet’s ecosystems in ways we don’t fully understand

Wildfires• Years of fire suppression have left forests

throughout the United States overstocked and in need of fuel load reduction

• Climate change, in places experiencing hotter, drier summers, may exacerbate this problem

Situation Becomes Opportunity• Increasing population and needs

• Existing forest cover

• Currently fossil fuels are main energy source

• How many strategies can we use to improve the situation?

• Wood is one of many possibilities

So What is Woody Biomass?

Woody biomass is the accumulated mass, above and below ground, of the roots, wood, bark, and leaves of living and dead woody shrubs and trees.

Potential Sources of Woody Biomass

• Urban waste wood Yard trimmings Storm damage

• Land-clearing debris

More Potential Sources of Woody Biomass

• Forestry residues Thinning for forest

health, wildfire risk reduction

Branches from harvesting

Processing residue

• Wood grown specifically for energy production

Other Sources of Biomass• Agricultural Residues

– Food-based– Non Food-based– Perennial Grasses– Animal Waste

Biomass availability in the U.S.

USDA/DOE, 2005

Potential Benefits of Using Wood

• Additional wood market for landowners interested in sustainable forestry

• Forest management can: reduce wildfire behavior enhance forest health improve wildlife habitat

More Potential Benefits

• Wood is a domestically plentiful renewable resource

• Useful way to process “waste wood”

• Can produce lower levels of sulfur, nitrogen, and heavy metals such as mercury than

fossil fuels• Carbon neutral• Creates local jobs

Understanding the Carbon Cycle

Potential Concerns about Using Wood

• Reduced soil fertility• Long term sustainable yields• Habitat change

Potential Solutions:• Best management practices• Sustainable forestry• Forest certification

Additional Concerns

• Unfamiliar technology• Cost, compared to alternatives

– Although cheaper than other renewables

Transporting and Handling Biomass

• Delivering energy, not volume or weight, is the objective• Transport costs can exceed 50% of total costs• Energy values are lower than most traditional wood markets

—so the less handling the better

1. Size reduction and method of loading

2. Moisture and ash content

3. Energy content in actual Btus per dry ash-free pound

4. Payload capacities of transport vehicles

Four Major Factors Influencing Transport Costs

Cheapest

Most

Expensive

•Harvest and process: $20-$30 per dry ton

•Transportation: $5-$12 per dry ton

Cost Assumptions for Wood SourcesAn Example

$-

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

0 2 4 6 8 10 12 14

Trillion BTUs Per Year

$/M

Mb

tuLocal Biomass Supply Curve

1 trillion btus=9.8 MW=3,934-8,852 homes

Deerhaven Facility, FL

Other SE US communities

$-

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

$3.50

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 MW$-

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

$3.50

0 500,000 1,000,000 1,500,000 Green Tons/year$-

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

$3.50

0 10,000 20,000 30,000 40,000 50,000 60,000 70,000

Truckloads/year

Truckloads/year

$-

$0.50

$1.00

$1.50

$2.00

$2.50

$3.00

$3.50

0 10,000 20,000 30,000 40,000 50,000

Homes/Year

Homes powered/year

Thermochemical Processes

Combustion Burning, or rapid oxidation, accompanied by release of energy in the form of heat and light.

Differences in Burners

• Coal systems much larger Individual units 100 to 1000 MW Typically pulverize the coal and burn it in

suspension

• Biomass systems much smaller Typically 1 to 50 MW Typically burn on a grate

Gasification

Gasification is a thermochemical process in which biomass at high heat is turned directly from a solid into a gaseous fuel called syngas (a mixture of carbon monoxide, hydrogen and some methane).

Pyrolysis Pyrolysis is the thermal degradation of organic components in biomass in the absence of oxygen. Major products are oil, gas, and char.

Bio-chemical Processes

Aerobic Digestion

Aerobic digestion is a process in which bacteria use oxygen to convert organic material into carbon dioxide. Products include nutrient-rich fertilizers and composts.

Anaerobic Digestion

Anaerobic Digestion is the decomposition of biomass by bacteria in the absence of oxygen. Biogas, or methane, is the primary product produced.

FermentationFermentation is a biological process in which enzymes produced by microorganisms cause chemical reactions to occur. Products include ethanol, commercial levels of therapeutic and research enzymes, antibiotics, and specialty chemicals.

Products

Woody Biomass Products

• Fiber• Building Materials• Chemicals• Fuels• Food

Bio-based Chemicals

• Medicines • Enzymes• Non-petroleum based rubbers• De-icers• Liquid Smoke

Bioenergy

• Energy produced from biomass including woody biomass, agricultural biomass, and other biological materials

• Includes electricity, heat, power, and transportation fuels

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